A label printer uses a continuous label including a band-like liner and a plurality of labels temporarily adhering to the liner, and prints information on each label as follows: it causes a thermal head and a platen roller to pinch one edge of the continuous label, rotates a platen roller to extract and feed the continuous label in a sheet shape, and prints information on each label while the sheet-like form is extracted and fed.
Some label printers have two print modes (i.e. continuous-print mode and separation print mode) for their operation (for example, Laid open patent publication JP 2006-150857 A). The continuous-print mode is a mode to continuously print information on two or more labels. The separation print mode is a mode to separate each label from the liner every time information is printed on each label. Such label printers include an optical sensor used for determination of a print mode, and a determination part configured to determine the print mode based on the intensity of light detected by the optical sensor.